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RE: Dates in URIs?

From: Williams, Stuart \(HP Labs, Bristol\) <skw@hp.com>
Date: Fri, 10 Nov 2006 10:09:23 -0000
Message-ID: <C4B3FB61F7970A4391A5C10BAA1C3F0D3EBFD2@sdcexc04.emea.cpqcorp.net>
To: "Schleiff, Marty" <marty.schleiff@boeing.com>, "Renato Iannella" <renato@nicta.com.au>, <noah_mendelsohn@us.ibm.com>, "John Cowan" <cowan@ccil.org>
Cc: <www-tag@w3.org>


> From the first paragraph of the introduction: "Such metadata 
> might include the title of a document, the creation date of 
> the resource, the MIME media type that is likely to be 
> returned by an HTTP GET, a digital signature usable to verify 
> the integrity or authorship of the resource content, or hints 
> about URI assignment policies that would allow one to guess 
> the URIs for related resources." 

I raised comments on exactly that paragraph with Noah [1] particularly:

>From [2]:

> > "Many URI schemes offer a flexible structure that can also be used
> > carry additional information, called metadata, about the resource."
> Stuart's comment:
> > Do you have an example of such a scheme.
> > I can't think of any!!!
> Sure, the http scheme for example.  I can encode into URIs in 
> that scheme creation dates, directory hierarchies, file 
> types, and all sorts of things.  It doesn't provide a 
> standard representation for any one of those, but that's not 
> the point:  it's a schema that "can be used" to carry such 
> information.  Indeed, the subject of the finding is when it 
> should be used in that way, and when consumers of URIs should 
> depend on it having been used that way.

Ok... I understand the point, but I still think that citing http as such
a scheme (as you do in your response above - not the document) sort of
over states things. In asking for examples, I was looking for examples
where explicit provision was made for carrying additional information,
with the explicit intent that the information be recoverable my
inspection of the URI. Maybe I read to much into the "CAN", but that is
what I read it as suggesting.

I guess that we can agree to differ on this one.

I think that the text remains ambiguous between "can" in the sense of 1)
a permission to use characteristics of a resource in assigning it a URI;
and 2) a reliable channel for metadata between provider and user of a

I read Noah's response to me as illustrative of 1). I think that many
people will read 2). 

That said, the finding does admit to the notion of documented URI
assignment policies (whether implicit in forms or some explicit document
eg. [2] which has been superseded though it's successors seem to me not
to state such a clear policy.). Without such a stated policy, people are
just guessing (maybe correctly) at the significance of substrings within
a URI. Even with a stated policy there may be varing levels of
commitment to the stability of the policy over time (even if there is a
commitment to the persistence of URI that have already been assigned).

> Marty.Schleiff@boeing.com; CISSP
> Associate Technical Fellow
> Cyber Identity Specialist
> Computing Security Infrastructure
> (206) 679-5933

[1] http://lists.w3.org/Archives/Public/www-tag/2006Sep/0095
[2] http://www.w3.org/2003/05/27-pubrules.html#rules
Received on Friday, 10 November 2006 10:09:38 UTC

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